$ \left(\dfrac{5}{3}\right)^{3}$
Solution: $= \left(\dfrac{5}{3}\right)\cdot\left(\dfrac{5}{3}\right)\cdot \left(\dfrac{5}{3}\right)$ $= \dfrac{25}{9}\cdot\left(\dfrac{5}{3}\right)$ $= \dfrac{125}{27}$